Surface modification of bentonites. V. Sol-gel transitions of Ca-montmorillonite in the presence of cationic end-capped poly(ethylene oxides)

摘要: The colloidal state of aqueous Ca 2+ -montmorillonite dispersions was modified with three types cationic end-capped poly(ethylene oxides). macromolecules were not only adsorbed at the external surfaces but also intercalated into dispersed montmorillonite particles. amounts and basal spacings (∼1.7 nm) comparable to corresponding Na + dispersions. oxides) protruding out interlayer spaces or surface determined behaviour phase diagrams (sol-gel diagrams) differed from those because different states both (Ca particles vs . delaminated -montmorillonite). oxide) containing showed fields sol flocs. Attractive gels formed in a few cases (TMA -PEO 1500 4000, THA 1500, 4000 20,000) distinctly lower gel strength than presence ions. On basis sol-gel diagrams, conditions (type concentration oxides), content) can be selected which lead peptization stable (sols). Addition enhance salt tolerance up 1000 mmol/l NaCl.